U.S. Pat. No. 3,967,273; issued June 29, 1976 and entitled "Method and Apparatus for Using Pushbutton Telephone Keys for Generation of Alpha-Numeric Information"; discloses a four column, three row pushbutton telephone keyboard by way of which a desired alpha-numeric symbol may be generated. The symbol is generated responsive to a two step finger repositioning process: (1) the operator locates and pushes a first button on which the desired symbol is labeled, each of the twelve buttons being labeled with at most a three-by-three array of symbols, and (2) the operator locates and pushes a second button, which second button is identified by the position of the desired symbol in the array labeled on the first button. The alpha-numeric symbols are arranged similar in layout to a standard typewriter keyboard thereby making it likely that anyone, who is familiar with the location of symbols on a typewriter keyboard, can quickly reposition his fingers to the desired symbol on the telephone keyboard. It is, however, no secret that the layout of symbols on the standard typewriter keyboard is an inefficient layout.
The typewriter originated as a purely mechanical device. Because of the crudity of its initial mechanical linkages, the symbols on the keys of early typewriters were intentionally positioned, or laid out, so as to slow the typist down to a speed compatible with the capabilities of the mechanical device. As a result, an awkward layout pattern is obtained. Unfortunately, the original awkward typewriter keyboard layout has persisted to the present time. A more efficient keyboard layout is disclosed in U.S. Pat. No. 2,040,248; issued May 12, 1936 to A. Dvorak et al. and entitled "Typewriter Keyboard." The Dvorak keyboard includes the letters being arranged in three rows. The upper row contains consecutively the letters p, y, f, g, c, r and l. The home row contains the letters a, o, e, u, i, d, h, t, n and s. The lower row contains the letters z, q, j, k, x, b, m, w and v. With that keyboard layout, Dvorak sought to produce an arrangement of the keys (having in mind the letter sequences found in the most commonly used words of a language) such that the automatic rhythm of the operator, in moving from one key to another key while typing a continuous flow of word-wholes and phrases-wholes, would better fit the mechanical rhythm of the typewriter.
Of course, other keyboard layouts are possible. For example, U.S. Pat. No. 3,879,722; issued Apr. 22, 1975 and entitled "Interactive Input-Output Computer Terminal with Automatic Relabeling of Keyboard"; discloses an arrangement for transferring symbols by optical means from a television screen display to a telephone keyboard having twelve pushbuttons. The disclosed optical means is a semitransparent mirror, which is interposed between the television screen and the pushbutton keyboard and which is oriented in such a manner that the operator of the terminal sees a virtual image of the television screen image overlaying the keyboard. By altering the symbols on the television screen, the keyboard layout may be dynamically adjusted. As a result, a lesser plurality of keys may be automatically relabeled by dynamically adjusting and by optically transferring a greater plurality of computer generated graphical or alpha-numeric symbols from the television screen to the telephone keyboard. Unfortunately, it appears that the operator must pre-learn sequences of displays to effectively use the U.S. Pat. No. 3,879,722 keyboard. That is, what a next-in-time display should be is not evident from the current-in-time display. Also, such pushbutton telephone or typewriter keyboards require repositioning of the operator's fingers in the use of the keyboard. Frequent repositioning of fingers consumes time and leads to an inefficiently operated keyboard.
To mitigate repositioning the operator's fingers among the keys, U.S. Pat. No. 3,633,724; issued Jan. 11, 1972 and entitled "Electric Typewriter Key and Keyboard Arrangement"; discloses a keyboard including eight keys, each key for generating five symbols and the keyboard for generating the 40 symbols common to a standard typewriter. Each key is arranged to be moved both axially and pivotally on the arcuate upper edges of a support member for selecting a respective one of the five symbols generated by depressing the key. Unfortunately, such a keyboard is not easy to use, for example, by an operator who is not skilled with the keyboard or by one who requires more than an occasional glance at the key labels to determine the symbol to be generated, e.g., the so-called hunt-and-peck typist. Also, while a finger need not be moved among the keys as with a standard keyboard, a finger is moved on a key for axially and/or pivotally moving the key. Such moving of the finger on a key tends toward an awkward relationship among the fingers as different keys are moved in different directions.